A new estimate suggests that the Milky Way contains more free-floating planets than stars. It’s a big claim, but an upcoming mission may actually prove it.
Rogue planets in our galaxy can number in the tens of billions and possibly even trillions, according to new research published in the Astronomical Journal. As confirmed, it means that the Milky Way hosts more unbound, starless planets than then stars. This estimate was developed in preparation for the Roman Galactic Exoplanet Survey (RGES), a five-year mission scheduled to begin over five to six years.
For the survey, NASAs Nancy Grace Roman Space Telescope– Planned to launch in 2025 – will continuously scan a narrow spot of sky in search of evil planets. The Roman space telescope is expected to detect and characterize hundreds of vicious planets, according to computer models described in the new paper, co-authored by astronomers Samson Johnson and Scott Gaudi of Ohio State University. This limited data problem will then allow astronomers to extrapolate and close the total number of orbiting planets across the entire Milky Way, which, as said, is enormously expected.
To date, astronomers have only found a small handful of evil planets, because they are so difficult to detect. To “actually get a full picture, our best bet is something like Roman,” Johnson said told Ohio State News, added that this is “a whole new frontier.”
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Not much is known about these starless planets, including the environment in which they were born. These planets can form around stars and then are ejected into interstellar space by powerful gravitational disturbances. It is also possible that these planets formed without an parent star, emerging of dense clouds of gas and dust in a process similar to how stars are born. Data collected by the Roman Space Telescope could test these theories.
Rogue planets are difficult to detect with conventional methods, but astronomers can sniff out signatures in accordance with the presence of planet-sized objects that travel through space, namely their ability to dispel space-time. For this purpose, the RGES team will use a method called gravity microlenses. NASA explains:
As a rogue planet closely joins a distant star from our vantage point, the star’s light will bend as it travels through the bent space-time around the planet. The result is that the planet acts as a natural magnifying glass, amplifying light from the background star. Astronomers see the effect as a peak in the brightness of the star as the star and planet come in line. Explain how the spike changes over time, showing clues to the mass of the rogue planet.
The incoming microlens signal will be over and very short, lasting no longer than a few hours or days, but the Roman space telescope will be sensitive enough to the task. In fact, this space-based observatory, which has its back to the sun, will be 10 times more effective at detecting evil planets than previous methods, such as ground-based telescopes, according to the paper.
For the planned microlensing study, the Roman telescope will look for a narrow strip of galaxy that extends from here to the center of the Milky Way – a distance of 24,000 light-years. The telescope will be staring at the sky in the same place for months on end of detecting the desired microlensing signature.
The technology must be sensitive enough to detect planets with masses as small as Mars, which is 10 times less massive then Earth. Planetary masses revealed by the microlensing technique, together with the vicious planet census, were able to improve our understanding of how these objects form.
As noted, the survey is expected to yield hundreds of rogue planets. As the Roman telescope finds much less or even none, astronomers will obviously have to re-evaluate their thinking on the matter or has the detection methodology. However, if the forthcoming research meets our expectations, it means that the total number of harmful planets in our galaxy is astronomically enormous, pointing to this dark, free-floating objects as an ubiquitous facility of the Milky Way.
And that’s a very spooky thought.
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